The present invention relates to a semi-liquid cementitious spray nozzle apparatus and particularly to such apparatus for pressurized application of a semi-liquid cementitious material such as cement, concrete, grout and the like to a backing or supporting surface.
In various structural applications, a vertical or other oriented wall surface is formed or covered with one or more layers of a cementitious material. For example, in-ground swimming pools may have an outer vertical wall structure lining the pool opening. The structural wall members or assembly provides an essentially continuous supporting structure for withstanding the water pressure created by the water in the pool. In one method of forming the wall, a heavy and thick cement or concrete may be applied to the earth opening to define the outer supporting wall. The cement material is for example as applied may have slump characteristics of two which upon application will be self supporting. The outer surface is then smoothed with an appropriate tool to form a smooth, final sealed surface to the pool wall. Many other structural and like applications are similarly provided with one or more finish coats of cement, grout, concrete or the like. The material is generally in a more or less semi-liquid state at the time of application, with the viscosity dependent upon application. As noted above, for forming a swimming pool, the cement is typically a slump of two. Pressurized spraying of the cementitious material provides a particularly satisfactory and cost efficient applicating system, particularly where large surface coatings are required. In such systems, a concrete pump is provided with an essentially continuous supply of the semi-liquid material with an appropriate viscosity for pumping through a hose or line. A nozzle is secured to the outermost end of the line which includes a connection 5 to a source of pressurized air. The nozzle includes suitable inlet or jet openings for introducing air pressure flow of air which discharges the material as a fan-shaped heavy spray emitted from the nozzle. The nozzle appears to act like a venturi device creating a fan-shaped discharge, which was approximately 11/2" thick with a diameter of about one foot. The operator will stand about 4 feet from the wall and the flexible hose structure allows the operator to manually move the nozzle over the surface to apply and build an appropriate wall structure of the desired and appropriate height, thickness and the like.
Various spray nozzle structures are commercially available. Because of the characteristic of the material being pumped, such as the heavy concrete for a swimming pool, special considerations are required in producing a satisfactory apparatus. Generally, a tubular body member includes a hose coupling at one end for interconnection to the hose or line from the concrete pump unit. A threaded connection to the hose is generally used. In addition, the assignee of this invention has also used a quick release clamp unit having pivoted clamp arms engaging a ledge portion on the nozzle for releasably attaching of the nozzle to the end of the hose. An outer air housing is threaded onto correspondingly threaded portions of the tubular body to define an annular encircling air chamber intermediate the length of the nozzle body. A plurality of holes are distributed about the hose body within the chamber. An air connecting pipe is also secured to the outer air housing and projects outwardly at a slight angle to generally define a pistol-type nozzle structure. The air pipe is connected to a suitable air hose for pressurization of the air chamber and introduction through the openings into the nozzle body for pressurized discharge of the cement or other material. Generally, a rubber-like reducing hose end is secured to the outer end of the body to reduce the diameter of the material jet emitted from the nozzle. Systems as described have been and are available and used in the pressurized application of coating to surfaces.
The nozzle elements are preferably formed of an appropriate steel because the material being transmitted is of a more or less abrasive characteristic depending upon the particular mixture. This creates a tendency to wear the surfaces of the nozzle structure. However, steel nozzle units are relatively heavy and use for an extended period is tiring. The standard commercial steel nozzle unit generally weigh between 6 and 8 pounds. Nozzles with aluminum components are also available providing a reduction in the weight and are generally available in a range of 3 to 4 pounds. The wear characteristic of the aluminum component nozzle is significantly less than that of the steel nozzle units.
Further, in all commercial units, servicing is a relatively time consuming and tedious process. The type of material with which the nozzle is used tends to lodge, clog, and set within the various openings, joints and the like. The nozzles must therefore be disassembled and thoroughly cleaned after each use. The cleaning must be rather carefully and thoroughly done to maintain the desired operating efficiency and effectiveness of the nozzle unit. Further, the threaded structures require care in cleaning to prevent damage to the threaded portions and the like.
In the spraying process, the operator often wishes to reorient the nozzle with respect to the surface. The concrete hose is a relatively heavy, stiff member and it is of course extremely difficult if at all possible to have any significant twisting of a nozzle when threaded directly onto a threaded coupling of the hose structure. Various swivel units are therefore sold for incorporation between the nozzle and the hose structure. Such swivel units permit the desired manipulation of the nozzle. However, the swivel units add additional weight to the nozzle unit and apparatus, and further increase operator fatigue. Further, such swivel units must of course be carefully constructed to operate in the severe environment present by pumping of cement, concrete, grout and the like and also require appropriate maintenance and cleaning.
In summary, although various commercially operable and usable nozzle units for pumping of a semi-liquid cementitious type material have been known and used for many years, there has been and continues to be a request and demand for a light-weight, long-life nozzle unit with a structure which can be quickly assembled and disassembled, easily cleaned thoroughly and permits convenient swiveling and manipulation of the nozzle unit for optimum application.